If someone is pulled over for drinking and driving, it's fairly easy to tell if someone's drunk: you can smell the booze, see them stumbling around, and a quick blow into the breathalyzer will tell you just how drunk they are. But knowing if someone is high while driving requires a different skill set.

"Do you ever smoke crack or anything like that?" Bellingham Police Officer, Zach Serad, is in the midst of Drug Recognition Expert Program field certification training. He's questioning a man high on heroin.

"Oh yeah, I mean I do that every once in a while," said Ken.

Ken, who was pulled off the street in downtown Seattle Tuesday morning by the Department of Corrections to act as a volunteer, is there to help officers test their drug detecting skills.

"They come down here and volunteer and we give them a sandwich and a soda and talk openly about their drug usage and we put them through the test," said Sgt. Mark Crandall, state coordinator for the program.

"We talk to them and calm them, make sure that we tell them they are not being arrested for anything," Sgt. Crandall said. "We just want their open cooperation. We allow them to use fake names. We ask them to submit to a series of tests. The series of tests are a standardized and systematic method of evaluating people who are under the influence of drugs."

"Are you still feeling the effects of the heroin right now?" Officer Serad asked Ken.

"Yeah, I mean I'm not sick, but I'm not feeling that great," Ken answered. "I mean, that dope lasts two, three or four hours. I used to sell dope in Tacoma. Now, my dope would hold you 22 hours because it was coming straight out of Mexico. I did that for a lot of years. I've been to the penitentiary 15 times."

Volunteers are surprisingly forthcoming and officers conduct an hour-long test that consists of measuring a volunteers pupils and checking their arms and hands for track marks from needle use.

"They get pretty graphic sometimes with abscesses and sores," Sgt. Crandall said. "We make sure that we have a discussion with them if they need any help, if we can get them into a treatment plan of some sort."

Sgt. Crandall says they sometimes ask volunteers to lie to officers, and tell them they've only been smoking pot, when they've actually been using meth, so the officers can test their skills.

"I pulled over somebody who was high on meth," Sgt. Crandall said. "He said, 'No no no no,' all the way through the process. All the way up to where I was getting the blood sample. Finally, at the end, and I had the blood sample in my hands, I said, 'Look, I don't know why you keep lying, saying, 'No no no no.' I jokingly said, 'I bet my badge and my next paycheck that you're going to have a stimulant on board. Which I believe is going to be meth.' He just started laughing and he says, 'Wow, you're really good. I'm not going to take that bet.' Just chatting with him, just kind of having fun, and he admitted that he'd been taking meth and I'm like, I know!"

Mark is an expert in detecting what drug someone is on, which comes in handy as a father to teenage daughters.

"With heroin we're going to see really tiny pupils, doesn't matter what the sunlight's like. Then we take them here for testing, we take them to a dark a room as possible and if their pupils don't get larger that's a sign. Heroin also comes with needle tracks."

As for meth:

"It's going to be the proverbial guy that's all amped up, he's going to be running around dancing, high energy. When we grab him, when we have to start talking with him, we're going to look at large pupils. Broad daylight, pupils are really large."

Marijuana is the number one drug people are pulled over for on Washington state roads. Mark says people who are legally smoking pot shouldn't be worried about getting pulled over during a routine stop, when they're sober, and getting in trouble for having cannabis in their blood. He says they only test for drugs when someone is showing signs of impairment, driving erratically or having had crashed their car.

"Nobody judges on people that are using in their private life or whatever they're doing. It's more of: don't use and drive. The number one killer of people in Washington state is people driving under the influence. So that's what we're trying to combat."